Near-infrared driven N2 fixation on ZnO–MXene (Ti3C2) heterostructures through pyroelectric catalysis

Temperature fluctuations caused by sunlight represent a form of low-quality thermal energy that is generally insufficient for driving chemical reactions. Here, we designed a ZnO–MXene (Ti3C2) heterostructure catalyst, which can harvest solar near-infrared (NIR) energy to drive the sluggish ammonia production reaction using water and N2 as the feedstock. Our research confirmed that ammonia was produced through a pyroelectric process, rather than a photocatalytic process. The ZnO–MXene heterostructure with ∼20 wt% of Ti3C2 exhibited a 6.5-fold improvement in activity compared to bare ZnO. The Ti3C2 not only harvests NIR energy to heat up the pyroelectric ZnO, but also traps the pyro electrons from ZnO and co-catalyzes the reduction of N2 to ammonia. This work offers a novel strategy for ammonia production utilizing the abundant solar NIR energy under ambient conditions.